As technology advances in the electronics industry, mobile phones and portable devices have become popular in our daily life. Mobile phones are usually equipped with flat panel displays to display information. Among various types of flat panel displays, liquid crystal display (LCD) is the most mature technology and is also most popularized. With the increasing demand on display size and resolution, the number of output buffers in the source driver increases as well. As a consequence, power consumed by the output buffers greatly determines the power consumption of the source driver. In addition, with the greater variety functions provided by the portable electronic products, low power requirement for the output buffers becomes very important.